Gas purification process



Sept. 22, 1931. F. w. SPERR, JR 1,824,103

GAS PURIFICATION PROCESS Filed April 9, 1925 2 Smets-Sheet l Sept. 22, 1931. F. w. SPERR. JR

GAS PURIFICATION PROCESS Filed April 9, 1925 2 Sheets-Sheet 2 lllllllffllllllllllll lll J INVENToR BY mw-M.

ATTORNEYTD Patented Sept. 22, 1931 narran STATES r ATENT OFFICE FREDERICK W. SPERR, JR., 'OF kTEITTSHCfRG-IH, PENNSYLVANIA, -ASVSIGNOR TO TH'E KOPPERS COMPANLOF PITTSBURGH, -PENNSYLVNIAA 'CORPORATION OFPENN'- SYLVANIA .Application filed April 9,

This invention relates to the removal of hydrogen sulphide vand other acidic vgaseous constituents .from :gases LAcontaining them, employing an alkaline absorbent liquid Whichfisrevivified by heating or aeration.

.The invention `relates more particularly to thc purification vof manufactured gases, such as coke oven gas, Watergas,andfthe like, from hydrogen lsulphide or other acidic gaseous 4 constituents contained by said gases. In the jmethod of acti-frying the spent purifying liquid after contact with the impurity laden gas, for further use, and to 'simplify `and cheapen the apparatus necessary for the said purification.

The present invention consists in a process of the above kind characterized 'by adding to the alkaline absorbent liquid a'metallic chloride to facilitate the expulsion of the K acidic gaseous constituents from the spent liquid.

r1`he invention also provides apparatus for carrying out'this process comprising an absorber, an actifier and a system for circulat- ,ing purifying liquid to and fro between the absorber and the actifier, characterized by the actifier containing devices for simul taneor-.slyY agitating and heating or aerating the spent liquid.

A further object of the invention is to increase the efficiency of the revivification i, ystaggeso that the same may `furnish a revivified suspension whereof the activity more nearly approaches that of a freshly prepared suspension than has heretofore been found feasible. flu respect tothis'obj ect, the inven- GAs runrrrca'rron .rnoonss 1925. Serial No. 21,981.

tion consists in 4adding a LpeptiZing-'or ant-iembodied and practiced, but Without limiting the yclaimed invention-to :such: illustrative finstance: 1

Figure l -is -an elevation ofrapparatus'for carrying out 'the improved process of the present invention, and

Figure'2is a plan view o'ffthesame apparatus with the toWersshoWn 'in section, on line 2-2 of Fig. 1.

In 'order that the invention may be-clearly understood, there will now be describeda method of operating apurificationprocess in `'accordance With the present invention, and in the apparatus illustrated. The treatment of the gas ytakes place Within ascrubbing tower, which may take "the form illustrated, wherein it is constituted of fa surrounding vertical shell .1, mounted upon a foundation 2, and .provided With various `inlets and outletsas Will be described or noted later. 'The gasenters the tower through aninlet man1- fold 3, `and is thereby distributed -to bells 4. The gas escapes :under theserrated edges of the bells 4 into the liquid `purifying medium, Where it is stripped 'of its hydrogen sulphide constituents, 'and a purification thereof is thereby effected. The puri-fied gaslescapes at the surfacefof'theliquid, and is removed from thetoiver through'an'outlet pipe "5 for Whateveruse is desired for it. The scrubber tower 1, Which-is not per se a'feature of theinvention, may take any desired form suitable to as rings of ceramic material, steel turnings, coke, wooden hurdles, and the like, or a centrifugal washer of the Feld type, or the gas might be allowed to diffuse in finely divided form into the liquid through some sort of porous medium, such as cloth, Filtros, earthenware, or other porous substance, as described in the assignees copending prior applications Ser. No. 718,253,1iled J une 6, 192e, Patent No. 1,578,560, and Ser. No. 730,676, filed Aug. 7, 1924, Patent No. 1,656,881.

The liquid, after contactiwiththe gas, passes out of the tower through outlets 6 and 7, through a seal 8, and into a spent liquor sump 9, which may if desired be provided with means for agitation. The spent liquor is then pumped from the sump 9 by means of a pump 10 into a heat exchanger 11, where it is heated by indirect Contact with hot liquid and discharges through a line 12 into an actifierevaporator 13. The latter may be equipped with -meansfor heating, such as steam tubes 14, and also with an agitator 15, driven by means of a pulley 16, and further with inlet and outlet pipes as described hereafter. By reason of the heat of the steam tubes, and the action of the agitator, the hydrogen sulphide is driven olf from the spent liquid, and escapes through an exit pipe 17 to be disposed of as desired. If it is desired, the vapors escaping through the exit pipe 17 may be passed through some form of indirect contact apparatus, whereby the heat of the same may be applied to preheat the liquid entering the evaporator. It has been found that the actification of the spent liquid is especially facile when that liquid is agitated during the heating process; experimental results have shown that but half the evaporation is required for actification when agitated as when the liquid is heated quietly.

Actiication of the liquid having been thus accomplished, the active suspension is pumped from the evaporator 13 by means of a pump 18, through the heat exchanger 11,

` where it gives up a part of its heat to the spent liquid about to enter the evaporator. The revivified liquid then passes by way of a pipe 19 into a cooler 19, where it is cooled to the proper temperature for absorption by indirect contact with cold water, and into the scrubber tower 1, through an inlet pipe 20. The cold water enters the cooler by an inlet 21 and leaves it by a discharge pipe 22.

The actiier, which in this instance is shown to be constituted in a fashion similar to the ordinary evaporator, may be so arranged as to permit the introduction of steam directly into the suspension, and might take the form of a steam still equipped with a plurality of bell trays, or any other form suitable to the carrying out of the actitication phase as de scribed above.

An alternate method of accomplishing the actiication ofthe spent liquid consists in subjecting the same to aeration or to a combination of heating and aeration and suitable apparatus may be provided for either of these purposes.

rlhe preferred absorbing liquid is a suspension of magnesium oxide in water and when the acidic gaseous constitutents such as hydrogen sulphide come into intimate Contact .with this suspension, the hydrogen sulphide is absorbed from the gases, and remains in the liquid, in the form of compounds with magnesium. It has been found, according to the present invention, that the prese-nce of a metallic chloride, for example magnesium chloride, greatly facilitates the removal of hydrogen sulphide from the suspension, with consequent reviviication of the suspension, when the liquid, after contact with the gas to be purified, is heated for this purpose. Consequently, the present invention provides a` liquid purifying medium consistingpreferably of a suspension of magnesium oxide in a solution of magnesium chloride. An example of a solution-suspension which has been used successfully consists of a 2.0 per cent suspenion of magnesium oxide in al 0.5 per cent solution of magnesium chloride. The acceleration of actification, when the spent solution is heated, is probably due to the acidity caused by the hydrolysis of the magnesium chloride. It has been demonstrated that, when the yratio of magnesium chloride to magnesium oxide is unity, only about onehalf as much of the solution-suspension need be.evaporated, for actiiication, as when no chloride is present.

The essential reactions that occur in the process are believed to be as follows: ln the Gas Absorption Stage:

uents such as hydro-cyanic acid are removed by analogous reactions.

The preferred aqueous suspension employed when a peptizing means is used contains 2% of magnesium oxide, 0.5% of magnesium chloride, and glycerine in the proportion of about 1% of the total liquid, as a peptizing means or anticoagulant. This proportion of glycerine is maintained in the suspension.

The addition of the peptizing agent such as glycerine prevents coagulation of the pari CJD ti'cle'sinsuspension, Which is believedto cause 'the revivli'fied liquid to be less active than a freshly prepared suspension, as is'sometimes experienced incarrying outthe process Without fa p'epti'zin'g agent.

`Glycerine employed in the above vproportionsiliasbeen found to give excellent results. Comparative tests in purifying a gas containing approximately 30.0 grains of hydrogen siilphide per hundred cubic feet employing 'a solutionsuspension of lmagnesi um chloride and megnesiuin oxide showed, after a given absorption period, that Without the presence 'of a -peptfi-Zing agent there occurred a loss of eflicien'cy ofthe revivified liquid relatively to a freshlyprepared suspension, which loss was reduced approximately 60% by the addition of glycerine.

l he invention as hereinabove set forth or exemplified may be variously practiced or embodied Within the scope of the claims hereinafter made.

I claim:

l'. Int'he Ytreatment of gas purification liquor, comprising a suspension of an alkaline earth metal compound adapted to take Vup acidic gaseous constituents from gas and to be rovivified upon reviviiication of the liquor, to improve its eiiiciency, the improvement which comprises adding and maintaining a peptizing agent in such liquor to substantially prevent coagulation of the particles during revivification of the liquor.

2. In the treatment of gas purification liquor, comprising a suspension of an alkaline earth metal compound adapted to take up acidic gaseous constituents from gas and to be revivified upon revivification of the liquor, to improve its efiiciency, the improvement which comprises adding and maintaining glycerine in such liquor as a peptizing agent to substantially prevent coagulation of the particles during revivification of the liq- 5. A process of purifying gases comprising Washing With an impurity absorbing agent consisting of an aqueous suspension of a magnesium compound and reviviiication by heating of the spent suspension, characterized by maintaining glycerine in the suspension to prevent coagulationof the yparticles in the'suspension.

6. A process of purifying gases comprising washing With an impurity absorbing agent consisting of an aqueous suspension of amagnesium compound and reifivii'ication by heating of the spent suspension, characterized by maintaining glycerine in `the suspension in proportion of about 1%, to prevent coagulation of the particles in the suspension.

7. A process of purifying gases which consists iii: passing the gas into contact With an alkaline absorbent solution containing an alkali-earth metal compound having an affinity for acidic constituents of the gas, and glycerine, to remove acidic gaseous constituents from the gas; then revivifying the spent liquid.

f 8. A process of purifyingy gases which consists in passing the gas into contact with an alkaline absorbent solution containing an alkali-earth metal compound having an aiiinity for acidic gaseous constituents ofthe gas, 'and a peptizing agent, to remove acidic gaseous constituents from the gas, then revivifying the spend liquid.A

9. A process of purifying gases which con- V sists in passing the gas into contact with an alkaline absorbent solution containing a magnesium compound having an aiiinity for acidic gaseous constituents 'of the gas, adding a peptizing agent to the spent solution, then revivifying such solution.

l0. A process of purifying gases which consists in passing the gas vinto Contact with an alkaline absorbent solution containing a magnesium compound having an afiinity for acidic gaseous constituents of the gas and glycerine, then revivifying the spent liquid.

. l1. A process of purifying gases of hydrogen sulphide and other acidic gaseous constituents which consists in passing the gas to be purified into contact with an alkaline absorbent solution containing magnesium chloride, adding glycerine thereto and then revivifyingthe fouled solution.

l2. The process'of purifying gases Which consists in passing the gas into contact With an alkaline absorbent solution containingt magnesium chloride to absorb the impurities from the gas, adding glycerine to the spent solution, then heating Athe spent Vsolution and agitating it to regenerate it.

i3. The process of purifying gases which consists in passing the gas into contact With an alkaline solution containing` an alkaliearth metal compound, to remove acidic gaseous constituents from vthe gas, adding glyceiine to the spent solution, then' heating and f agitating the spent solution containing the glycerine to eliminate absorbed acidic gaseous constitutents and thereby regenerate the solution. y

.14, A process of purifyinggas of hydroen sulphide which consists in passing the `as to be puriied into contact With a solution ontaining magnesium oxide and magnesium chloride` adding glycerine to the spent solution and then reyivifying the solution.

l5. A process of purifying gases of hydrogen sulphide and other acidic gaseous constituents comprising: making a suspension of magnesium oxide in a solution of magnesium chloride; passing the gas in yContact with said liquid to effect absorption of said impurities by reaction of the magnesium oxide with. the impurities of said gas; drawing off the liquid fouled by reaction of said magnesium oxide with the impurities of said gas; revivifying said foul liquid by decomposing the impurity containing magnesium compound under the influence of heat and reaction promoted by the magnesiun'i chloride, so as to restore the suspension oi magnesium oxide in a solution of magnesium chloride; employing such revivied suspension-solution for further gas purification, and continuing the cycle, and replenishing losses in the system by adding thereto both magnesium oxide and magnesium chloride to maintain in circulation the required proportion of both.

16. A process of purifying gases of hydrogen sulphide and other acidic gaseous con-V stituents comprising: making a 0.5% solution of magnesium chloride containing ap proximately 2% of magnesium oxide in suspension; passing the gas in contact with said liquid to effect absorption of said impurities by reaction of the magnesium oxide with the impurities of said gas; drawing off the liquid fouled by reaction of said magnesium oxide with the impurities of said gas; revivifying said foul liquid by decomposing VIthe impurity containingmagnesium compound under the iniiuence of heat and reaction promoted by the magnesium chloride, so

as to restore the suspension of magnesium oxide in a solution of magnesium chloride; employing such revivilied suspension-solution for further gas purification and continuing the cycle and replenishing losses in the system by adding thereto both magnesium oxide and magnesium chloride to maintain in circulation the required proportions of both.

l?. fi process of purifying gases of hydrogen sulphide and other acidic gaseous constituents comprising: making a suspension of an alkali-earth metal compound in a solution of chloride of the same alkali-earth metal; passing the gas in contact with said liquid to effect absorption of said impurities by reaction of the alkali-earth metal compound With the impurities of the gas; drawing olf the liquid fouled by reaction of said alkali-earth metal compound With the impurities of the gas; revivifying said foul liquid by decomposing the impurity containing alkali-earth metal compound under the influence of heat and reaction promoted by the alkali-earth metal chloride, so as to restore the suspension of alkali-earth metal compound in a solution of alkali-earth metal chloride, employing such revivified suspension-solution for further gas purification, and continuing the cycle, and replenishing losses in the system by adding thereto both the alkali-earth metal compound and chloride of the same alkali-earth metal to maintain in circulation the required proportions of both.

18. A process of purifying gases which comprises, passing the gas in contact with a liquid containing both an alkali-earth metal oxide and chloride of the same alkaliearth metal, to remove acidic gaseous constituents from the gas, then heating the spent liquid and, simultaneously with such heating, agitating the spent liquid to regenerate it.

In testimony whereof I have hereunto set my hand.

FREDERICK WV. SPERR, JR. 

